Process of purifying pyroligneous acid.



UNITED s'ra rns PATENT orrion.

, JAMES ROBERT GA ROWAY, or GLASGOW, SCOTLAND.

PROCESS OFPURIFYING F YRQLIGNEOUS AClD.

- certain new and useful Process of Purifying Pyroligneous Acid, of which the following is a specification.

'I his invention relates to improvements in the manufacture of acetic acid, acetic-acid salts, and by-productsresulting from such manufacture, and has for its object the provision of a process whereby"relatively purer and better compounds of acetic acid as well as the acid itself may be produced at less ex pense of time and labor, a higher yield of acetic acid and its salts and the by-products incidental to the manufacture of these may be secured, and an easier and more thorough elimination of contaminatin materials naturally coexistent with acetic acid in its commercial source may be made possible.

To this end itis proposed to neutralize crude pyroligneous acid-the commercial source of acetic acid with a magnesium compound possessing the ability to displace the replaceable hydrogen of acids, to elimi nate contammating material, to treat the acid magnesium salt by suitable manipula tion and technique adapted for such recovery.

sodium carbonate, calciuiin or sodium acetate resulting therch'om. In my improved process I substitute for such neutralizing agents n'iaterial or materials which perform Hitherto it has been the practice to neutralize pyrohgneous acid with either lime or Specification of Letters Patent. Application filed October 6, 1905. Serial No. 281.70%.

the neutralizing actionin a better man;

ner and yield acetic-acid salts more readily soluble than are either calcium or sodium acetate.

Dependent upon the particular color of acetic-acid salt desired, pyrcl cons acid is either distilled, after the tar has been allowed to settle, or at once neutralized. If a prelj-r rtinary distilling process is employed, a gray an of acetic acid "results. Direct neutralization-that is, neutralization without a prei l l V l l l Patented Feb. 19, 1907.

aeir. salt. For the production of gray salt I employ oxid of magnesium as neutralizing agent. For producing brown salt I employ warbonate of magnesia.- In either case acetate of magnesium results, and because such salt is readily soluble in water it is possible to boil in or ,concentrate such magnesiumacetate solution to a markedlyheavy density,

an easy and thorough elimination of tar be-- In this respect sulfuric acid of proper strength and in quantities sullicient to decompose all of the magnesium acetate -that is, to liberate all of the acetic acid combined with magnesium -is added and the entire material subjected to distillation, whereby acetic acid is readily given off while sulfate of magnesia remains in the still. An alternative process for the herein-described manipulation of the decomposed magnesium-acetate solutionthat is, What is now a solution of magnesium sulfate and free acetic acid'is its further concentration with subsequent crystallization of the sulfate of magnesium from such mother-liquor,

The removal of these crystals of magnesium. 3 5

sulfate is variously effected by means of suitable presses or centrifugal machines known for such separatory manipulation, the mother-liquor being after such separation subjected to the distillation previously described.

Acetic acid of high purity results from either of the described equivalent separatory rnzmipulations while the magnesium sulfate is still in'a crude state because of contamination with tar. For purification this material is heated to a high temperature in a suitable furnace, the tar being removed hereby by volatilization and burning. The residuum;

of crude magnesium sulfate is further puri- 10o iied by repeated crystallizations, comn'iercial .psom salts resulting.

What 1 claim, and desire to secure by Let tors Patent, is

t. dueing acetic acid, and by-products from cr ude-pyroligneous acid, consisting in neutralizing the acid with a basic magnesium liminary distillation-yields a brown acetic- 55 The herein-described )roccss for )1'0- 10 the non-volatile port'mnsz 2. Theherein-described process for producing acetic acid, and by-products from crude pyrcligneous acid, consisting in neutralining the aeisl With magnesium Xid, concentrating the neutralized solution, removing crintaminating materials, saturating with a mineral acid, and separating the resulting acetic acid from the magnesium I salt prorlneeil.

3. The herein-described process for producing acetic acid, and by products frgm crude pyr'oligneous acid consisting in neutralizing the acid with magnesium oxid, concentrating the neutralizedsolutien, removing contaminating materials, saturating with sulfuric acid and separating the acetic acid from the magnesium sulfate.

In Witness whereof I have hereunto set my hand in the presence of two Witnesses.

JAMES ROBERT GARROVVAY. Witnesses:

JOHN LID LE, CATHERINE HAMILTON. 

